Cyanate ester resins, epoxy resins and bismaleimide resins comprise the three major classes of thermosetting resins. Thermosetting resins can be used in a wide variety of applications, such as, for example, in the preparation of advanced composite materials, in the preparation of printed circuit board compositions, in the formation of glob-top structures, in a variety of encapsulation applications, in the preparation of adhesive compositions (e.g., die attach compositions), and the like.
Cyanate esters in particular are currently employed for the rapid curing of adhesive compositions used to bond semiconductor devices or chips, also known as dice, to carrier substrates. Such adhesive compositions include, in addition to the cyanate ester, thermally and/or electrically conductive filler, alkylphenol (as a proton donor participating in the cyclotrimerization cure of the cyanate ester monomer), and a curing catalyst dissolved in the alkylphenol.
Cyanate ester adhesive compositions have eliminated many of the deficiencies inherent in epoxy adhesives and polyamide adhesives, such as low glass transition temperature, high degree of ionic contamination, retention of solvent and lengthy cure. Nevertheless, there still remains room for improvement of die attach pastes containing electrically conductive filler in a variety of ways, e.g., by reducing the cost of preparation, by improving the ease of preparation, by improving the working pot life of the preparation, by avoiding the use of potentially detrimental components (e.g., alkylphenols are acidic species, which are potentially corrosive), by avoiding the use of volatile components (which upon cure tend to bleed out, which may lead to the creation of voids in the cured resin), by reducing the propensity of such materials to uptake moisture, by improving the resistance of such materials to hydrolysis, and the like.